Touchpad devices are usually installed in notebooks for controlling the movement of cursor.
There are two ways for touchpad devices to control the cursor movement, one is to move the cursor according to the relative coordinate and the other is the absolute coordinate.
The way of using relative coordinate to control the cursor movement is the same as that used for controlling cursor with a mouse. That is to say, the distance and the direction of the cursor is determined by finger's slipping direction and accumulated slipping displacement on touchpad. Most users do not get used to the relative coordinate mode since they have to slip their fingers on the small area of the touchpad repeatedly to accumulate enough amount of displacement if they want to move the cursor for a longer displacement on the screen.
To solve the problem of the relative coordinate operation mode, there exists an absolute coordinate operation mode for touchpad devices in the prior art. In absolute coordinate operation mode, a cursor on a screen is moved to a coordinate according to a finger's touch point on the touchpad. So users do not have to slip their fingers on the touchpad when using an absolute operation mode.
However, since the area of a touchpad is much smaller than that of a screen, the coordinate of the touch point on the touchpad usually can't be projected on the screen precisely. It is therefore users are not able to finely move a cursor to a desired position one time in absolute coordinate operation mode.
Therefore, there is a need of providing an improved system for controlling cursor movement with touchpad devices.